The asteroid impact roughly 66 million years ago that wiped out three-quarters of plant and animal species, including the dinosaurs, dropped temperatures globally below freezing for several years. The new assessment, reported in the journal Geographic Research Letters, gives scientists a much clearer picture of the climate catastrophe following the event. BCC reports: The UK geophysicist was the co-lead investigator on the 2016 project to drill into what remains of the impactor's crater under the Gulf of Mexico. She and colleagues spent several weeks retrieving the rock samples that would allow them to reconstruct precisely how the Earth reacted to being punched by a high-velocity space object. Their study suggests the asteroid approached the surface from the north-east, striking what was then a shallow sea at an oblique angle of 60 degrees. Roughly 12km wide and moving at about 18km/s, the stony impactor instantly excavated and vaporized thousands of billions of tonnes of rock. This material included a lot of sulphur-containing minerals such as gypsum and anhydrite, but also carbonates which yielded carbon dioxide. The team's calculations estimate the quantities ejected upwards at high speed into the upper atmosphere included 325 gigatones of sulphur (give or take 130Gt) and perhaps 425Gt of carbon dioxide (plus or minus 160Gt). The CO2 would eventually have a longer-term warming effect, but the release of so much sulphur, combined with soot and dust, would have had an immediate and very severe cooling effect.